1. Field of the Invention
The present invention relates to a reciprocatory piston type multi-cylinder refrigerant compressor for a refrigeration system, and more particularly, it relates to a reciprocatory piston type compressor provided with a rotary valve element for controlling the suction of a refrigerant gas before compression from a suction chamber into respective cylinder bores; the rotary valve may also control discharge of the refrigerant gas after compression from respective cylinder bores toward a discharge chamber.
2. Description of the Related Art
Reciprocatory piston type refrigerant compressors such as a wobble plate operated reciprocatory piston type variable displacement compressor, and a swash plate operated reciprocatory piston type fixed displacement compressor are conventionally used for compressing a refrigerant circulating through a refrigeration system of e.g., an automobile air conditioner. The reciprocatory piston type compressor is provided with an axial cylinder block having a plurality of cylinder bores arranged parallel with a drive shaft of the compressor and a plurality of single headed or double headed pistons reciprocated in the respective cylinder bores to compress the refrigerant in the form of a gas. For example, the compressor having single headed pistons is also provided with a housing attached to one of the axial ends of the cylinder block via a valve plate to define a suction chamber therein from which the refrigerant gas is supplied into respective cylinder bores so as to be compressed, and a discharge chamber therein toward which the compressed refrigerant gas is discharged from the respective cylinder bores. When the refrigerant gas is supplied from the suction chamber into the respective cylinder bores, the gas passes through suction ports formed in the valve plate and closably opened by suction valves arranged so as to be in contact with one end face of the valve plate on the side thereof confronting respective cylinder bores. The suction valves are opened when a pressure level in each cylinder bore is lower than a given low pressure level. Similarly, when the compressed refrigerant gas is discharged from the respective cylinder bores toward the discharge chamber, the compressed refrigerant passes through discharge ports formed in the valve plate and closably opened by discharge valves arranged so as to be in contact with the other end face of the valve plate on the side thereof confronting the discharge chamber. The discharge valves are opened when the pressure level in each cylinder bore is higher than a given high pressure level. It should, however, be noted that these suction and discharge valves arranged on opposite sides of the valve plate of the conventional compressor have the form of a flapper or reed valve, respectively. Namely, each of the suction and discharge valves in the flapper form is made of a thin elastic plate material so that the valve is constantly elastically urged toward the closing position thereof. Therefore, the flapper valve must always be moved from the closing to opening position thereof against the elastic force exerted by the valve per se, and accordingly during the opening of the suction or discharge valve in the flapper form, a considerable amount of refrigerant pressure loss occurs thereby lowering the volumetric efficiency of the compressor.
Further, when the suction or discharge valve in the flapper form returns to the closing position thereof, it strikes against the end face of the valve plate and produces a loud noise, and may additionally be apt to be damaged or broken.
U.S. Pat. Nos. 4,749,340, 4,764,091, and 4,781,540 disclose several constructional improvements of the flapper valve that enhance the volumetric efficiency of the reciprocatory piston type compressor and solve the noise problem. Nevertheless, a further innovative improvement of the function and performance of the suction and discharge valves of the reciprocatory piston type compressor has been requested.